Updated translations.
Replaced definitions of the same delete method in models with a mixin.
Fixed inconsistency in how HTTP errors are returned.
Added layouts for all defined HTTP errors.
Removed unneeded custom frontend exceptions.
Minor page title tweaks.
Simplified structure of exceptions in web service.
Removed APIError class.
Added Less compiler into the VM.
Added a way to set preferred Less compilation option.
Added setuptools into requirements file.
Revert "Added setuptools into requirements file."

This reverts commit ccc6c230625fb8db5db7abc51840a65208731df1.
Merge branch 'delete-mixin'
Merge branch 'translations'
Merge branch 'memcache'
Merge branch 'errors'

Conflicts:
	critiquebrainz/frontend/apis/musicbrainz.py
Merge branch 'less-vagrant'
Merge branch 'master' into config

Conflicts:
	critiquebrainz/config.py.example
	critiquebrainz/default_config.py